Autonomous coverage robots

ABSTRACT

An autonomous coverage robot includes a body, a drive system disposed on the body, and a cleaning assembly disposed on the body and configured to engage a floor surface while the robot is maneuvered across the floor surface. The cleaning assembly includes a driven cleaning roller, a cleaning bin disposed on the body for receiving debris agitated by the cleaning roller, and an air mover. The cleaning bin includes a cleaning bin body having a cleaning bin entrance disposed adjacent to the cleaning roller and a roller scraper disposed on the cleaning bin body for engaging the cleaning roller. The cleaning bin body has a holding portion in pneumatic communication with the cleaning bin entrance, and the air mover is operable to move air into the cleaning bin entrance.

CROSS REFERENCE TO RELATED APPLICATIONS

This U.S. patent application is a continuation-in-part of, and claimspriority under 35 U.S.C. §120 from, U.S. patent application Ser. No.11/758,289, filed on Jun. 5, 2007, which is a continuation of, andclaims priority under 35 U.S.C. §120 from, U.S. patent application Ser.No. 11/633,885, filed on Dec. 4, 2006 (now U.S. Pat. No. 7,441,298,issued on Oct. 28, 2008), which claims priority under 35 U.S.C. §119(e)to U.S. Provisional Application 60/741,442, filed on Dec. 2, 2005. Thedisclosures of these prior applications are considered part of thedisclosure of this application and are incorporated herein by referencein their entireties.

TECHNICAL FIELD

This invention relates to autonomous coverage robots.

BACKGROUND

Autonomous robots are robots which can perform desired tasks inunstructured environments without continuous human guidance. Many kindsof robots are autonomous to some degree. Different robots can beautonomous in different ways. An autonomous coverage robot traverses awork surface without continuous human guidance to perform one or moretasks. In the field of home, office and/or consumer-oriented robotics,mobile robots that perform household functions such as vacuum cleaning,floor washing, patrolling, lawn cutting and other such tasks have beenwidely adopted.

SUMMARY

An autonomous coverage robot will encounter many obstacles whileoperating. In order to continue operating, the robot will need tocontinually avoid obstacles, and in cases where trapped by fabric,string, or other entangling soft media, free itself.

In one aspect, an autonomous coverage robot includes a body, a drivesystem disposed on the body and configured to maneuver the robot, and acleaning assembly disposed on the body and configured to engage a floorsurface while the robot is maneuvered across the floor surface. Thecleaning assembly includes a driven cleaning roller, a cleaning bindisposed on the body for receiving debris agitated by the cleaningroller, and an air mover. The cleaning bin includes a cleaning bin bodyhaving a cleaning bin entrance disposed adjacent to the cleaning rollerand a roller scraper disposed on the cleaning bin body for engaging thecleaning roller. The cleaning bin body has a holding portion inpneumatic communication with the cleaning bin entrance for receivingdebris, and the air mover is operable to move air into the cleaning binentrance. The roll scraper includes a substantially linear edge disposedsubstantially parallel to and substantially spanning the cleaningroller. In some implementations, the cleaning assembly includes an airguide configured to direct an air flow of the air mover over thecleaning roller and into the cleaning bin entrance. The air guide may bearranged to direct the flow of air along a path substantially tangent tothe cleaning roller and coincident with a point slightly above thecenter line of the cleaning roller.

In another aspect, an autonomous coverage robot includes a body, a drivesystem disposed on the body and configured to maneuver the robot, acleaning assembly disposed on the body and configured to engage a floorsurface while the robot is maneuvered across the floor surface. Thecleaning assembly includes a driven cleaning roller, a cleaning bindisposed on the body for receiving debris agitated by the cleaningassembly, and an air mover. The cleaning bin includes a cleaning binbody having a cleaning bin entrance disposed adjacent to the cleaningroller and a roller scraper disposed on the cleaning bin body forengaging the cleaning roller. The cleaning bin body has a holdingportion in pneumatic communication with the cleaning bin entrance forreceiving debris, and the air mover is configured to move air into thecleaning bin entrance. The cleaning assembly housing includes an airguide configured to direct an air flow of the air mover over thecleaning roller and into the cleaning bin entrance. The air guide may bearranged to direct the flow of air along a path substantially tangent tothe cleaning roller and coincident with a point slightly above thecenter line of the cleaning roller.

Implementations of the previous two aspects of the disclose may includeany of the following features. In some implementations, the rollerscraper is disposed an interference distance D of between about 0.25 mmand about 3 mm (preferably 0.75 mm) into an outer diameter of thecleaning roller. The roller scraper may be disposed at the cleaning binentrance (e.g., so that debris scraped from the cleaning roller fallsinto the cleaning bin). In some examples, the air mover is disposedinside the cleaning bin body substantially near an upper rear portion ofthe cleaning bin body. The air mover defines a longitudinal axisdisposed at an angle of between about 15° and about 75° with respect toa longitudinal axis defined by the cleaning bin body. In someimplementations, the robot includes an air mover guard disposed betweenthe air mover and the holding portion of the cleaning bin. The air moverguard includes a filter for filtering debris from air passingtherethrough. The air mover guard may be removably attached to thecleaning bin body and defines an asymmetric shape, such that the airmover guard is received by the cleaning bin body in a singleorientation. In some implementations, the cleaning assembly includes acleaning assembly housing and first and second driven cleaning rollersrotatably coupled to the cleaning assembly housing. The first cleaningroller includes bristles and the second cleaning roller includesflexible flaps. The roll scraper is disposed to engage the firstcleaning roller. In implementations that include an air guide, the airguide is configured to direct an air flow of the air mover over thecleaning rollers and into the cleaning bin entrance. The first andsecond driven cleaning rollers may be driven in opposing directions todirect agitated debris up and between the two cleaning rollers into theair flow of the air mover. In some examples, the driven cleaningroller(s) is the air mover and generates a flow of air into the cleaningbin entrance and/or the holding portion of the cleaning bin.

In yet another aspect, a cleaning bin for a coverage robot includes acleaning bin body having a cleaning bin entrance, an air mover disposedon the cleaning bin body and configured to draw air into the cleaningbin entrance, and a roller scraper disposed on the cleaning bin body forengaging a cleaning roller of a coverage robot. The cleaning bin bodyhas a holding portion in pneumatic communication with cleaning binentrance for receiving debris. The roll scraper includes a substantiallylinear edge for placement substantially parallel to and substantiallyspanning the cleaning roller.

Implementations of this aspect of the disclosure may include any of thefollowing features. In some implementations, the roller scraper isdisposed at the cleaning bin entrance. The air mover may be disposedinside the cleaning bin body substantially near an upper rear portion ofthe cleaning bin body. In some examples, the air mover defines alongitudinal axis disposed at an angle of between about 15° and about75° with respect to a longitudinal axis defined by the cleaning binbody. The cleaning bin may include an air mover guard disposed betweenthe air mover and the holding portion of the cleaning bin. The air moverguard includes a filter for filtering debris from air passingtherethrough. The air mover guard may be removably attached to thecleaning bin body and defines an asymmetric shape, such that the airmover guard is received by the cleaning bin body in a singleorientation.

In another aspect, a cleaning bin for a coverage includes a cleaning binentrance, a holding portion in pneumatic communication with the cleaningbin entrance for receiving debris, an air conduit in pneumaticcommunication with the holding portion, and a roller scraper disposed atthe cleaning bin entrance for engaging a cleaning roller of a coveragerobot. The air conduit establishes pneumatic communication with an airmover of a cleaning robot while received by the cleaning robot. The rollscraper comprises a substantially linear edge for placementsubstantially parallel to and substantially spanning the cleaningroller.

In another aspect, an autonomous coverage robot includes a chassis, adrive system mounted on the chassis and configured to maneuver therobot, an edge cleaning head carried by the chassis, and a controllercarried by the chassis. The edge cleaning head is driven by an edgecleaning head motor and may rotate about a non-horizontal axis. The edgecleaning head extends beyond a lateral extent of the chassis to engage afloor surface while the robot is maneuvered across the floor. The edgecleaning head may be disposed on or near a peripheral edge of the robot.A brush control process, independent of drive processes, on a controllerthat controls robot operation is configured to monitor motor currentassociated with the edge cleaning head. The brush control process on thecontroller is also configured to reverse bias the edge cleaning headmotor in a direction opposite to the previous cleaning direction afterdetecting a spike (e.g., transient or rapid increase in motor current)or in general an elevated motor current motor (to substantiallyneutrally rotate and/or be driven to rotate at the same speed as a anunwinding cord, string, or other tangled medium), while continuing tomaneuver the robot across the floor performing uninterrupted coverage orcleaning of the floor or other motion behaviors. In one implementation,the brush control process on the controller, following an elevated edgecleaning head motor current, reverse biases the edge cleaning head motor(to substantially neutrally rotate and/or be driven to rotate at thesame speed as a an unwinding cord, string, or other tangled medium) andsubsequently or concurrently passes a signal to a drive motor controlprocess, directly or indirectly via a supervising process, so that theunwinding may occur at the same time that the robot drives substantiallybackwards, alters a drive direction, and moves the robot forward.

In one implementation, the edge cleaning head includes a brush withbristles that extend beyond a peripheral edge of the chassis. In oneexample, the edge cleaning head includes at least one brush elementhaving first and second ends, the bush element defining an axis ofrotation about the first end normal to the work surface. The edgecleaning head may rotate about a substantially vertical axis. In oneinstance, the edge cleaning head includes three brush elements, whereeach brush element forms an angle with an adjacent brush element ofabout 120 degrees. In another instance, the edge cleaning head comprisessix brush elements, where each brush element forms an angle with anadjacent brush element of about 60 degrees.

In another implementation, the edge cleaning head comprises a rotatablesqueegee that extends beyond a peripheral edge of the chassis. Therotatable squeegee may be used for wet cleaning, surface treatments,etc.

In yet another implementation, the edge cleaning head includes aplurality of absorbent fibers that extend beyond a peripheral edge ofthe chassis upon rotation of the cleaning head. The plurality ofabsorbent fibers may be used like a mop to clean up spills, cleanfloors, apply surface treatments, etc.

The robot may include multiple cleaning heads (e.g., two or three)carried by the chassis. In one example, the robot further includes amain cleaning head carried by the chassis, a cleaning head extendingacross a swath covered by the robot, which forms the main work width ofthe robot, and which may be driven to rotate about a horizontal axis toengage a floor surface while the robot is maneuvered across the floor.The main cleaning head may include a cylindrical body defining alongitudinal axis of rotation parallel to the work surface, bristlesdisposed on the cylindrical body, and flexible flaps disposedlongitudinally along the cylindrical body. The brush control process onthe controller is configured to reverse bias the rotation of the maincleaning head (to substantially neutrally rotate and/or be driven torotate at the same speed as a an unwinding cord, string, or othertangled medium), in response to an elevated main cleaning head motorcurrent, while a motion control process independently continues tomaneuver the robot across the floor. In another example, the robotincludes two main cleaning brushes carried by the chassis and driven torotate about a horizontal axis to engage a floor surface while the robotis maneuvered across the floor. The two main cleaning brushes may bedriven to rotate in the same or opposite directions.

In another aspect, a method of disentangling an autonomous coveragerobot includes placing the robot on a floor surface, the robotautonomously traversing across the floor surface in a forward directionof the robot while rotating about a non-horizontal axis an edge cleaninghead carried by the chassis and driven by an edge cleaning head motor.The edge cleaning head extends beyond a lateral extent of the chassiswhile engaging the floor surface. The robot independently provides areverse bias for the edge cleaning head motor (to substantiallyneutrally rotate and/or be driven to rotate at the same speed as a anunwinding cord, string, or other tangled medium), in response to anelevated edge cleaning head motor current while continuing to maneuveracross the floor surface.

In one implementation, the brush control process on the controller ofthe robot determines movement of the robot in the forward directionbefore (independently of robot motion control) reversing the rotation ofthe edge cleaning head in response to an elevated cleaning head motorcurrent. The brush control process of the robot may (independently ofrobot motion control) reverses the rotation of the edge cleaning head inresponse to an elevated edge cleaning head motor current for a period oftime. In one example, after the brush control process reverses therotation of the edge cleaning head, the brush control process maydirectly or through a supervising process pass a signal to the motioncontrol process of the robot to move in a reverse direction, alter adrive direction, and moves in the drive direction.

In another implementation, the robot also includes a main cleaning brushcarried by the chassis, which may be driven to rotate about a horizontalaxis to engage the floor surface while the robot is maneuvered acrossthe floor. The robot independently reverses the rotation of the maincleaning brush in response to an elevated main cleaning head motorcurrent while continuing to maneuver across the floor surface. The brushcleaning process of the robot may also determine movement of the robotin the forward direction before independently reversing the rotation ofthe main cleaning brush in response to an elevated main cleaning brushmotor current. Furthermore, the brush cleaning process of the robot mayalso reverse the rotation of the main cleaning brush for a certainperiod of time or in intervals.

In another aspect, an autonomous coverage robot includes a drive system,a bump sensor, and a proximity sensor. The drive system is configured tomaneuver the robot according to a heading (turn) setting and a speedsetting. The bump sensor is responsive to a collision of the robot withan obstacle in a forward direction. The proximity sensor is responsiveto an obstacle forward of the robot at a proximate distance but notcontacting the robot, e.g., 1-10 inches, preferably 1-4 inches. Themotion control processes of the drive system may also be configured toreduce the speed setting in response to a signal from the proximitysensor indicating detection of a potential obstacle, while continuing acleaning or coverage process, including advancing the robot according tothe heading setting. Furthermore, the motion control processes of thedrive system may also be configured to alter the heading (turn) settingin response to a signal received from the bump sensor indicating contactwith an obstacle.

In some instances, the motion control processes of the drive system maybe configured to alter the heading setting in response to the signalsreceived from the bump sensor and one or more side proximity sensors tofollow a perimeter of the obstacle. In other instances, the drive systemmay be configured to alter the heading (turn) setting in response to thesignals received from the bump sensor and the proximity sensor to directthe robot away from the obstacle. In one example, the drive system isconfigured to maneuver the robot at a torque (e.g., motor current ormotor resistance) setting and the drive system is configured to alterthe motor current or motor resistance setting in response to a signalreceived from the bump sensor indicating contact with an obstacle. Thedrive system may increase the motor current or motor resistance settingin response to a signal received from the bump sensor indicating contactwith an obstacle.

The proximity sensor may include a plurality of sets of at least oneinfrared emitter and receive pair, directed toward one another toconverge at a fixed distance from one another, substantially asdisclosed in “Robot obstacle detection system”, U.S. Pat. No. 6,594,844,herein incorporated by reference in its entirety. Alternatively, theproximity sensor may include a sonar device. The bump sensor may includea switch, a capacitive sensor, or other contact sensitive device.

The robot may be placed on the floor. In yet another aspect, a method ofnavigating an autonomous coverage robot with respect to an object on afloor includes the robot autonomously traversing the floor in a cleaningmode at a full cleaning speed. Upon sensing a proximity of the objectforward of the robot, the robot reduces the cleaning speed to a reducedcleaning speed while continuing towards the object until the robotdetects a contact with the object. Upon sensing contact with the object,the robot turns with respect to the object and cleans next to theobject, optionally substantially at the reduced cleaning speed. Therobot may follow a perimeter of the object while cleaning next to theobject. Upon leaving the perimeter of the robot, the robot may increasespeed to a full cleaning speed. The robot may maintain a substantiallyconstant following distance from the object, may maintain a followingdistance smaller than the extent of extension of an edge cleaning heador brush beyond a following side of the robot body, or may substantiallycontact the object while cleaning next to the object in response to theinitial, reduced cleaning speed contact with the object. In one example,the following distance from the object is substantially a distancebetween the robot and the object substantially immediately after thecontact with the object. In another example, the following distance fromthe object is between about 0 and 2 inches.

In one instance, the robot performs a maneuver to move around the objectin response to the contact with the object. The maneuver may include therobot moving in a substantially semi-circular path, or a succession ofalternating partial spirals (e.g., arcs with progressively decreasingradius) around the object. Alternatively, the maneuver may include therobot moving away from the object and then moving in a directionsubstantially tangential to the object.

Upon sensing a proximity of the object forward of the robot, the robotmay decrease the full cleaning speed to a reduced cleaning speed at aconstant rate, an exponential rate, a non-linear rate, or some otherrate. In addition, upon sensing contact with the object, the robot mayincrease a torque (e.g., motor current) setting of the drive, mainbrush, or side brush motors.

In yet another aspect, an autonomous robot includes a chassis, a drivesystem mounted on the chassis and configured to maneuver the robot, anda floor proximity sensor carried by the chassis and configured to detecta floor surface below the robot. The floor proximity sensor includes abeam emitter configured to direct a beam toward the floor surface and abeam receiver responsive to a reflection of the directed beam from thefloor surface and mounted in a downwardly-directed receptacle of thechassis. The floor proximity sensor may be a substantially sealed unit(e.g., in the downward direction) and may also include abeam-transparent cover having a forward and rearward edge disposedacross a lower end of the receptacle to prohibit accumulation ofsediment, “carpet fuzz”, hair, or household dust within the receptacle.The cover may include a lens made of an anti-static material. Theforward edge of the cover, i.e., the edge of the cover in the directionof robot motion, at the leading edge of the robot, is elevated above therearward edge. The lower surface of the receptacle may be wedge shaped.In one example, the floor proximity sensor includes at least oneinfrared emitter and receiver pair, substantially as disclosed in “Robotobstacle detection system”, U.S. Pat. No. 6,594,844.

In one implementation, the drive system of the robot includes at leastone driven wheel suspended from the chassis and at least one wheel-floorproximity sensor carried by the chassis and housed adjacent one of thewheels, the wheel-floor proximity sensor configured to detect the floorsurface adjacent the wheel. The drive system may also include acontroller configured to maneuver the robot away from a perceived cliffin response a signal received from the floor proximity sensor. In someinstances, the drive system includes a wheel drop sensor housed near oneof the wheels and responsive to substantial downward displacement of thewheel with respect to the chassis. The drive system may include avalidation system that validates the operability of the floor proximitysensors when all wheels drop. The validation is based on the inferencethat all wheels dropped are likely the result of a robot being liftedoff the floor by a person, and checks to see that all floor proximitysensors do not register a floor surface (either no reflection measured,or a reflection that is too strong). Any sensor that registers a floorsurface or a too strong reflection (e.g., indicating a blocked sensor)is considered blocked. In response to this detection, the robot mayinitiate a maintenance reporting session in which indicia or lightsindicate that the floor proximity sensors are to be cleaned. In responseto this detection, the robot will prohibit forward motion until avalidation procedure determines that all floor proximity sensors areclear and are functional. Each wheel-floor and wheel drop proximitysensors may include at least one infrared emitter and receiver pair.

The details of one or more implementations of the disclosure are setforth in the accompanying drawings and the description below. Otheraspects, features, and advantages will be apparent from the descriptionand drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 shows an above-perspective view of an example autonomous coveragerobot.

FIG. 2 shows a below-perspective view of an example autonomous coveragerobot.

FIG. 3 shows an exploded view of an example autonomous coverage robot.

FIG. 4 shows a front-perspective view of an example main cleaning headwhich may be incorporated in an autonomous coverage robot.

FIG. 5 shows an exploded view of an example main cleaning head which maybe used with an autonomous coverage robot.

FIG. 6A is an exploded view of an exemplary cleaning bin.

FIGS. 6B and 6C are cross-sectional views of the exemplary cleaning binshown in FIG. 6A.

FIG. 6D is a perspective view of an exemplary main cleaning head.

FIG. 6E is a bottom perspective view of the exemplary main cleaning headshown in FIG. 6D.

FIG. 7A shows an above-perspective view of an example edge cleaning headwhich uses a rotatable brush.

FIG. 7B shows an exploded view of an example edge cleaning head.

FIG. 7C shows schematic views of a tilt of an example edge cleaninghead.

FIG. 7D shows an example of an edge cleaning head with a rotatablesqueegee.

FIG. 8A shows a bumper which may be used with autonomous coverage robot.

FIG. 8B shows kinetic bump sensors and proximity sensors.

FIG. 9A shows a block diagram of an exemplary robot; FIGS. 9B and 9Cshow flow charts describing motion control and brush operation.

FIG. 10 shows floor proximity sensors and an attachment brace which maybe used for detecting an adjacent floor.

FIGS. 11 and 12 show side and exploded views of a floor proximitysensor.

FIG. 13 shows an exploded view of a cover used with the floor proximitysensor shown in FIGS. 11 and 12.

FIG. 14 is an exploded view showing an example of a caster wheelassembly.

FIG. 15 is an exploded view showing an example of a wheel-drop sensor.

FIG. 16 is a cross-sectional view showing an example of a caster wheelassembly.

FIGS. 17A-H illustrate examples of methods for disentangling coveragerobots with various configurations of cleaning heads.

FIG. 17A illustrates a method of disentangling which may be used with acoverage robot having an agitating roller

FIG. 17B illustrates a method of disentangling which may be used with acoverage robot having an agitating roller and a brush roller.

FIG. 17C has a side view and a bottom view that illustrates a method fordisentangling a coverage robot with dual agitating rollers.

FIG. 17D illustrates an alternate method of disentangling with the robotshown in FIG. 17C.

FIG. 17E illustrates a method of disentangling a coverage robot with twoagitation rollers and a brush roller.

FIG. 17F illustrates another method of disentangling the coverage robot.

FIG. 17G has a side view and a bottom view illustrating adisentanglement method with a coverage robot 300 with two agitationrollers and two air ducts.

FIG. 17H has a side view and a bottom view illustrating adisentanglement method with a coverage robot 300 with two agitationrollers, a brush roller and two air ducts.

FIG. 18 is a sectional view of an exemplary autonomous coverage robotincluding a cleaning bin.

FIG. 19A is a front perspective view of an exemplary cleaning bin.

FIG. 19B is an exploded view of the cleaning bin of FIG. 19A.

FIGS. 19C and 19D are rear perspective views of the cleaning bin of FIG.19A.

FIG. 19E is a front view of the cleaning bin of FIG. 19A.

FIG. 19F is a side view of the cleaning bin of FIG. 19A.

FIG. 19G is a section view of the cleaning bin of FIG. 19E along line19G-19G

FIG. 20 is a section view of a cleaning bin.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

FIGS. 1-3 show above-perspective, below-perspective, and exploded viewsof an example autonomous coverage robot 100. Robot 100 has a chassis102, a drive system 104, an edge cleaning head 106 a, and a controller108. Drive system 104 is mounted on the chassis 102, and is adifferential drive (left and right wheels near to or on the centerdiameter of the robot and independently speed controllable) configuredto maneuver robot 100. Edge cleaning head 106 a is mounted to extendpast the side edge of chassis 102 for removing dirt and debris below andimmediately adjacent to robot 100, and more particularly to sweep dirtand debris into the cleaning path of the main cleaning head 106 b as therobot cleans in a forward direction. In some implementations, the mainor edge cleaning heads 106 b, 106 a may also be used to apply surfacetreatments. A controller 108 (also depicted in FIG. 9A) is carried bychassis 102 and is controlled by behavior based robotics to providecommands to the components of robot 100 based on sensor readings ordirectives, as described below, to clean or treat floors in anautonomous fashion. A battery 109 may provide a source of power forrobot 100 and its subsystems. A bottom cover 110 may protect internalportions of robot 100 and keep out dust and debris.

Drive system 104 includes a left drive wheel assembly 112, a right drivewheel assembly 114 and a castor wheel assembly 116. Drive wheelassemblies 112, 114 and castor wheel assembly 116 are connected tochassis 102 and provide support to robot 106. Controller 108 may providecommands to the drive system to drive wheels 112 and 114 forward orbackwards to maneuver robot 100. For instance, a command may be issuedby controller 108 to engage both wheel assemblies in a forwarddirection, resulting in forward motion of robot 100. In anotherinstance, a command may be issued for a left turn that causes left wheelassembly 112 to be engaged in the forward direction while right wheelassembly 114 is driven in the rear direction, resulting in robot 100making a clockwise turn when viewed from above.

FIGS. 4 and 5 show front perspective and exploded views of a maincleaning brush 111 which may be incorporated in the main cleaning head106 b of the robot 100 via attachment to chassis 102. General structureof a robot and cleaning heads as disclosed herein is similar to thatdisclosed in U.S. Pat. No. 6,883,201, herein incorporated by referencein its entirety, except when so noted. In general, when a robot brushbecomes entangled with cords, strings, hair, fringes or tassels, thebrush motor may encounter overcurrent or temperature rise, and may causeincreased energy consumption, poor cleaning, slowing or jamming of thebrush. If the robot is so controlled or the entangling item is heavy orsecured, the robot may be held in place, and if sensors are available todetect stasis, may stop moving and thereby fail to clean. A robot thatgets stuck during its working routine must be “rescued” and cleaned inorder to continue autonomous function. Theoretically, there may beadditional expenditure of energy to combat static or dynamic friction inthe drive wheels, caster, bin squeegee and cleaning head drive train(reverse-drive). The fringes/tassels/cords may wind tightly around asmallest wind diameter of the cleaning brush (e.g., usually the core ofa brush 111, if the brush 111 includes only bristles). If the smallestdiameter of the cleaning brush 111 is solid (no elasticity), additionalenergy may be required to overcome static or dynamic friction in a geartrain of the cleaning head and the brushes in contact with the floor,e.g., when the brush is rotated in the opposite within the cleaning headin order to unwind the fringes/tassels/cords. If the tassel or string ispermitted to continue winding about the brush, it may be necessary toremove the brush 111 from the cleaning head 106 b in order to remove theentanglement. Main cleaning head 111 has baffles or soft flaps 113 andbristles 115 arranged along a cleaning head body 117. Soft flaps 113disposed along the length of cleaning head body 117 may minimize staticfriction. Cleaning head body 117 may be rotated about its horizontalaxis so that it engages the floor surface while robot 100 is movingacross a floor, causing baffles 113 and bristles 115 to agitate dirt anddebris which may be on the floor's surface. Controller 108 may beconfigured to reverse bias the rotation of main cleaning head 111 (i.e.,provide sufficient reverse current to permit the cleaning brush tofreely rotate when the robot draws out and unwinds an entanglement as itmoves away in a forward direction) following a sharp rise in or anelevated main cleaning head motor current, while continuing to conduct acleaning cycle or other cycle as the controller 108 executes individualmotion control behaviors to move the robot 100 across the floor. A rim113 a of soft flaps 113 in this case can become the smallest diameter ofcleaning head 111. Rim 113 a is flexible (pliable, soft), so as torequire little energy to deform, potentially diverting energy away fromthat required to initiate robot 100 movement. A momentary delay in abrush gear train encountering static friction provides an opportunityfor robot 100 to resume movement, thereby enabling easierdisentanglement of brushes. Similarly, a cord or tassel may become lessentangled about the larger diameter of the rim 113 a (in comparison to acore such as core 117 or even smaller core) simply because the brush 111does not complete as many turns per unit length of entangled cord ortassel. Furthermore, a length-wise scooped (curved) nature of the flaps13 further acts as a spring forcing the tassels/fringes to unravel/openduring the momentary lag between the robot being set in motion and areverse bias to bias back-driving of the entangled cleaning head 111.Bristles 115 may be used primarily used to clean, while flaps 113 may beused primarily for disentanglement purposes. This allows robot 100 tocontinue to clean (agitate the carpet) if an entangled string snaps offand gets retained by flaps 113 in cleaning head 111. Other robot detailsand features combinable with those described herein may be found in thefollowing U.S. Provisional Patent Application No. 60/747,791, the entirecontents of which are hereby incorporated by reference.

FIG. 6A is an exploded view showing an example of a cleaning bin 600.The cleaning bin 600 includes a bottom housing 602, a middle housing604, a top housing 606, a debris cavity 607, a filter cavity 608, afilter cavity cover 609, a debris squeegee 610 having first and secondportions 610 a and 610 b, and a vacuum fan 612. Referring to FIG. 2, thechassis 102 defines a bin receiving slot 601 where the cleaning bin 600is housed.

Together, the top housing 606 and the middle housing 604 form a debriscavity 607. The debris cavity 607 has at least one opening 617 at itsforward side adjacent to the cleaning assembly 112. Through theopening(s), the debris cavity 607 may collect debris from the edgecleaning head 106 and/or the main cleaning head 106 b.

Together, the bottom housing 602 and the middle housing 604 may alsoform a filter cavity 608 that stores debris vacuumed from the worksurface. The debris squeegee 610 scrubs the work surface and directsdebris into the debris cavity 607. The vacuum fan 612 is attached to thetop side of the middle housing 604. The vacuum fan 612 creates a suctionpath from the work surface at the debris squeegee 610 and through thefilter cavity 608. A filter below the vacuum fan 612 prevents debrisfrom exiting the filter cavity 608 and entering the vacuum fan 612.

The filter cavity cover 609 is rotatably attached to the middle housing604 and is configured to move between a closed position and an openposition, which exposes the filter cavity 608 and a filter forservicing.

The cleaning bin 600 may also include a filter cavity cover springactuator 611 that biases the filter cavity cover 609 in the openposition. When the cleaning bin 600 is secured to the chassis 102 thefilter cavity cover 609 is held in a closed position. When the filtercavity cover 609 is removed from the chassis 102, the filter cavitycover spring 611 rotates the filter cavity cover 609 open, exposing thefilter cavity 608 for removal of debris. In one example, the cleaningbin 600 may also include a latch to hold the biased filter cavity cover609 in the closed position, until a user releases the latch, therebyallowing the filter cavity cover spring 611 to rotate the cover open.

The vacuum fan 612 includes a power connector 614. The power connector614 provides power to the vacuum fan 612 from the electric battery 302.The power connector 614 protrudes through an opening 616 in the tophousing 606. This allows the power connector 614 to mate with a powerconnector in the chassis 102 when the cleaning bin 600 is placed in areceptacle within the chassis 202.

FIGS. 6B and 6C are cross-sectional views showing examples of thecleaning bin 600 including cleaning bin covers. FIG. 6B shows an exampleof the cleaning bin 600 having a cleaning bin cover 702 hinged at thebin housing 606. The bin cover 702 enclose a robot side of the filterbin 600. The bin cover 702 may be opened to empty the cleaning bin 600,and in particular, the debris the filter cavity 608. A bin filter 704below the vacuum fan 612 retains debris vacuumed into the filter cavity608 along the suction path. The bin covers 702 may have attached springs706 or another device that bias the bin covers 702 in an open position.

In certain implementations, the bin covers 702 open as the cleaning bin600 is removed from the coverage robot 100 (as shown in FIGS. 6B and6C). Alternatively, the bin cover 702 may open when a bin cover latch isreleased. The latch retains the bin cover 702 in a closed position, suchas during operation of the coverage robot 100. The latch may be releasedto open the bin cover 702 and empty the cleaning bin 600.

In some examples, as shown in FIG. 6B, the vacuum fan 612 draws air intothe filter cavity 608 as well as the debris cavity 607. The middlehousing 604 and/or the top housing 606 define respective air ports 913A,913B to pneumatically connect the debris cavity to the vacuum fan 612.As the vacuum fan 612 moves air (and debris) into the cleaning bin 600,the air is drawn through the debris squeegee 610 into the filter cavity608 and over the cleaning head 111 into the debris cavity 607 by anegative pressure created within the cleaning bin 600 with respect tooutside of the cleaning bin 600. Enough air can be moved over thecleaning head so as to strip filaments, such as hair, off the cleaninghead 111 and draw them into the debris cavity 607.

FIG. 6D is a perspective view showing an example of the main cleaninghead 106 b. The main cleaning head 106 b includes a cleaning headhousing 1062, which carries a cleaning head assembly 1064. The cleaninghead assembly 1064 may be movable with respect to the cleaning assemblyhousing 1062 and the coverage robot 100. The cleaning head assembly 1064carries the main cleaning brush 111 and a cleaning drive motor 1066 (ascan be seen, although a multiplicity of bristle groups are provided onthe brush 111, only a few are depicted for clarity).

FIG. 6E is a bottom perspective view of the main cleaning head 106 bshowing an example of the cleaning head assembly 1064. The cleaning headassembly 1064 includes a main cleaning brush 111 a and a secondarycleaning brush 111 b. The main cleaning brush 111 is rotatably coupledto the cleaning head assembly housing 1062. The secondary cleaning brush111 b includes flexible flaps. The secondary brush 111 b may rotate inthe opposite direction to the main brush 111 a, so that debris impelledby the main brush 111 a is caught and directed up and over the secondarybrush 111 b. In addition, the flexible flaps may brush the work surfaceclean as the second cleaning head 111 b rotates.

FIGS. 7A and 7B show above-perspective and exploded views of edgecleaning head 106. Edge cleaning head 106 a is carried by chassis 102and driven by an edge cleaning head motor 118 and drive transmission 119to rotate a brush 120 about a non-horizontal axis. Brush 120 has brushelements 122A-F that extend beyond a peripheral edge of chassis 102.Each brush element 122A-F forms an angle of about 60 degrees withadjacent brush elements and is tipped with bristles extending along theaxis of the elements. Brush 120 may be rotated about a vertical axis,such that the ends of bush elements 122A-F move normal to the worksurface. Edge cleaning head 106 may be located near the edge of robot100 so that brush 120 is capable of sweeping dirt and debris beyond theedge of chassis 102. In some implementations, the edge cleaning head 106operates about an axis offset (tilted) from a vertical axis of therobot. As shown in schematic form in FIG. 7C the brush 106 may betilted, in both forward and side to side directions (i.e., tilteddownward with respect to the plane of wheel contact about a line about45 degrees from the direction of travel within that plane), in order tocollect debris from outside the robot's periphery toward the main workwidth, but not disturb such collected debris once it is there orotherwise eject debris from the work width of the robot. The axis offsetis optionally adjustable to customize the tilt of the cleaning head 106to suit various carpet types, such as shag.

Other configurations of edge cleaning heads may also be used with robot100. For example, an edge cleaning head may have three evenly-spacedbrush elements separated by 120 degrees. FIG. 7D shows another exampleof an edge cleaning head 124 in which a rotatable squeegee 126 is usedin place of a brush. In other configurations, an edge cleaning head mayhave one or more absorbent fibers that extend beyond a peripheral edgeof chassis 102.

FIG. 8A shows a bumper 130 which may be used with the autonomouscoverage robot 100. FIG. 8B shows proximity sensors 134 which may behoused within bumper 130. Drive system 104 may be configured to maneuverrobot 100 according to a heading setting and a speed setting. Proximitysensors 134 may sense a potential obstacle in front of the robot.

FIG. 9A shows a schematic view of electronics of the robot 100. Therobot 100 includes a controller 103 which communicates with a bumpermicro-controller 107A, that together control an omni-directionalreceiver, directional receiver, the wall proximity sensors 134, and thebumper switches 132. The controller 103 monitors all other sensorinputs, including the cliff sensors 140 and motor current sensors foreach of the motors.

Control of the direction and speed of the robot 100 may be handled bymotion control behaviors selected by an arbiter according to theprinciples of behavior based robotics for coverage and confinement,generally disclosed in U.S. Pat. Nos. 6,809,490 and 6,781,338, hereinincorporated by reference in their entireties (and executed bycontroller 108), to reduce the speed magnitude of robot 100 whenproximity sensor 134 detects a potential obstacle. The motion behaviorsexecuted by the controller 108 may also alter the velocity of robot 100when kinetic bump sensors 132 detect a collision of robot 100 with anobstacle. Accordingly, referring to FIG. 9A, robot 100 traverses a floorsurface by executing a cruising or STRAIGHT behavior 900. When robot 100detects a proximate, but not yet contacting obstacle via proximitysensors 134, robot 100 executes a gentle touch routine 902 (which may bea behavior, a part of a behavior, or formed by more than one behavior),in which robot 100 does not proceed at full cleaning speed into theobstacle; but instead reduces its approach speed from a full cleaningspeed of about 300 mm/sec to a reduced cleaning speed of about 100mm/sec via controller 108 toward the potential obstacle, such that whena collision does occur, the collision is less noisy, and less likely tomar surfaces. The overall noise, the potential damage to the robot 100or the object being collided thereby is reduced. When robot 100 detectscontact with the object via kinetic bump sensors 132, robot 100 executesone of the following routines: bounce 910, follow obstacle perimeter912, alter drive direction and move away from object 914, or alter drivedirection to curve to approach the object and follow along it (e.g., awall). Bounce 910 entails robot 100 moving so as to bounce along theobject. Follow obstacle perimeter 912 entails robot 100 using proximitysensors 134 to follow along a perimeter of the object at a predefineddistance to, for example, clean up close to the object and/or clean tothe very edge of a wall. The robot 100 continuously cleans the room, andwhen it detects a proximate object (which may be a wall, table, chair,sofa, or other obstacle) in the forward direction, it continues cleaningin the same direction without interruption, albeit at a reduced speed.In predetermined and/or random instances, the robot 100 will bump theobject, turn in place so that the edge of the main cleaning head 106 bis as close to the wall as possible, and closely follow the object onthe side of the robot, essentially at the reduced cleaning speed, suchthat the side/edge brush 106 a collects debris or dirt from the cornerbetween the floor and the wall or obstacle. Once the robot 100 leavesthe wall, after a predetermined and/or randomized distance withinpredetermined limits, the robot 100 increases its speed up to fullcleaning speed. On other occasions, it will bump the object, turn inplace until facing away from the object or wall, and immediately proceedaway from the object or wall at full cleaning speed.

The robot 100 employs a behavioral software architecture within thecontroller 103. While embodiments of the robot 100 discussed herein mayuse behavioral based control only in part or not at all, behavior basedcontrol is effective at controlling the robot to be robust (i.e. notgetting stuck or failing) as well as safe. The robot 100 employs acontrol and software architecture that has a number of behaviors thatare executed by an arbiter in controller 103. A behavior is entered intothe arbiter in response to a sensor event. In one embodiment, allbehaviors have a fixed relative priority with respect to one another.The arbiter (in this case) recognizes enabling conditions, whichbehaviors have a full set of enabling conditions, and selects thebehavior having the highest priority among those that have fulfilledenabling conditions. In order of decreasing priority, the behaviors aregenerally categorized as escape and/or avoidance behaviors (such asavoiding a cliff or escaping a corner), and working behaviors (e.g.,wall following, bouncing, or driving in a straight line). The behaviorsmay include: different escape (including escaping corners,anti-canyoning, stuck situations, “ballistic” temporary fire-and-forgetmovement that suppress some avoid behaviors, e.g., as disclosed in U.S.Pat. No. 6,809,490) cliff avoiding, virtual wall avoiding (a virtualwall may be a beacon with a gateway beam), spot coverage (covering in aconfined pattern such as a spiral or boustrophedon patch), align(turning in place, using side proximity sensors to align with a forwardobstacle encountered while obstacle following, e.g., an inside corner),following (representing either or both of substantially parallel or bumpfollowing along an obstacle using a side proximity sensor or bumper thatextends to the side of the robot), responding to a bump in order to“bounce” (a behavior that occurs after the robot bumps an object), anddrive (cruising). Movement of the robot, if any, occurs while a behavioris arbitrated. If more than one behavior is in the arbiter, the behaviorwith a higher priority is executed, as long as any correspondingrequired conditions are met. For example, the cliff avoiding behaviorwill not be executed unless a cliff has been detected by a cliffdetection sensor, but execution of the cliff avoiding behavior alwaystakes precedence over the execution of other behaviors that also havesatisfied enabling conditions.

The reactive behaviors have, as their enabling conditions or triggers,various sensors and detections of phenomena. These include sensors forobstacle avoidance and detection, such as forward proximity detection(multiple), forward bump detection (multiple), cliff sensors (multiple),detection of a virtual wall signal (which may instead be considered acoverage trigger). Sensors of these types are be monitored andconditioned by filters, conditioning, and their drivers, which cangenerate the enabling conditions as well as record data that helps thebehavior act predictably and on all available information (e.g.,conversion to one-bit “true/false” signals, recording of likely angle ofimpact or incidence based on strength or time differences from a groupof sensors, or historical, averaging, frequency, or varianceinformation).

Actual physical sensors may be represented in the architecture by“virtual” sensors synthesized from the conditioning and drivers.Additional “virtual” sensors that are synthesized from detectable orinterpreted physical properties, proprioceptive or interpreted upon therobot 100, such as over-current of a motor, stasis or stuck condition ofthe robot 100 (by monitoring a lack of odometry reading from a wheelencoder or counter), battery charge state via coulometry, and othervirtual sensors.

In addition, reactive behaviors can act according to enabling conditionsthat represent detected phenomena to be sought or followed. A beam orwireless (RF, acoustic) signal can be detected without direction; or insome cases with direction. A remote beam or marker (bar code,retro-reflective, distinctive, fiducial, or natural recognized by visionlandmark) giving a direction can permit homing or relative movement;without direction the robot 100 can nonetheless move to servo on thepresence, absence, and/or relative strength of a detected signal. Thereflection of a beam from the robot 100, edge, or line can be similarlydetected, and following behaviors (such as obstacle following by therobot 100) conducted by servoing on such signal. A debris or artifactsignal can be collected by monitoring debris or objects collected by ortraversed by the robot, and that signal can be an enabling condition fora reactive behavior controlling a spot coverage pattern.

The robot 100 maintains concurrent processes, “parallel” processes thatare not generally considered reactive behaviors. A scheduler may benecessary to allocate processor time to most other processes, e.g.,including the arbiter and behaviors, in a co-operative or othermultitasking manner. If more threading is available, less processes maybe managed by the scheduler. As noted, filters and conditioning anddrivers, can interpret and translate raw signals. These processes arenot considered reactive behaviors, and exercise no direct control overthe motor drives or other actuators. In addition, in the presentembodiment, brush motor controller(s) control the main and side brushes,although these may alternatively be controlled by dedicated brushbehaviors and a brush control arbiter.

In accordance with another example, the gentle touch routine 902 mayemploy an infrared proximity detector 134 that should go off (i.e., whena receiver receives from a reflection originating in the overlappingspace of an emitter and receiver angled toward one another) from about 1to 10 inches (preferably, from 1 to 4 inches. This distance is selectedin order to be within the effective range of the IR proximity orcross-beam sensor 134, yet with sufficient time to slow the mobile robot100 before a collision with a detected obstacle). Conventional proximitysensors return a signal strength depending on obstacle albedo;cross-beam sensors 134 can be thresholded for various albedos intrudingin the specific distance from the sensor where the receiver andemitter's beam/field cross. Additionally, slowing down based on aproximately detected wall may be suppressed in or turned off by theuser, independently of the bump sensor 132. Controller 108 may slow therobot's descent substantially in a steady reduction then cruise slowly.Controller 108 may execute an S-curve slowly over about 3 inches, canslow down steadily but at an accelerating or decelerating rate overabout 3 inches. During escape behaviors, for example, panic, stasis,stuck, anti-canyoning, the robot may essentially can be turn off theproximity sensors 134—usually by not using the proximity sensors 134 asan enabling condition for any escape behavior or some avoidancebehaviors

Drive system 104 may be configured to reduce the speed setting inresponse to a signal from proximity sensor 134 which indicatingdetection of a forward obstacle, while continuing to advance the robot100 and work the floor or surface according to the existing headingsetting. Drive system 104 may be configured to alter the heading settingin response to a signal received from bump sensor 132 that indicatescontact with an obstacle. For example, drive system 104 may beconfigured to alter the heading setting in response to the signalsreceived from the bump sensor 132 and the proximity sensor 134 such thatrobot 100 follows a perimeter of the obstacle. In another example, drivesystem 104 may be configured to change heading to direct robot 104 awayfrom the obstacle.

Proximity sensors 134 may include one or more pairs of infrared emittersand receivers. For instance, a modulated emitter and a standard receivermay be used. A light pipe (not shown), collimating or diffusing optics,Fresnel or diffractive optics, may be used in some implementations toeliminate blind spots by providing a more uniform light pattern or alight pattern more concentrated or more likely to be detected in highprobability/high impact areas, such as the immediate forward direction.Alternatively, some implementations may make use of sonar or other typesof proximity sensors.

In some implementations, kinetic bump sensor 132 may include amechanical switch 130. In some implementations, bump sensor 132 mayinclude a capacitive sensor. Other types of contact sensors may also beused as well.

Drive system 104 may be configured to maneuver robot 100 at a torque (ormotor current) setting in response to a signal received from bump sensor132 which indicates contact with an obstacle. For instance, drive system104 may increase the torque (or motor current) setting in response to asignal received from the bump sensor indicating contact with anobstacle.

In another example method of navigating an autonomous coverage robotwith respect to an object on a floor, robot 100 may be initially placedon the floor (or may already be on the floor, e.g., if the robot startsitself from a charging dock) with robot 100 autonomously traversing thefloor in a cleaning mode at a full cleaning speed. If robot 100 senses anearby object in front of robot 100, it reduces the cleaning speed(e.g., to a reduced cleaning speed) and continues moving toward theobject and working/cleaning the floor until detecting impact, which islikely to be with the object but may be another object. Upon sensingimpact with an object, robot 100 turns with respect to the object thatit bumped and cleans next to, i.e., along, the object. Robot 100 may,for instance, follow the object's perimeter while cleaning along or nextto the object. In another instance, robot 100 may maintain a somewhatconstant following distance from the object while cleaning next to theobject in response to the contact with the object. The followingdistance from the object may be a distance between robot 100 and theobject immediately after the contact with the object, for instance, 0 to2 inches. The distance is optionally less than the distance that theside or edge brush unit 106 a extends beyond the side of the robot.

Robot 100 may, in some instances, perform a maneuver to move around theobject in response to the contact with the object. For example, robot100 may move in a somewhat semi-circular path around the object, or asuccession of alternating partial spirals (e.g., arcs with progressivelydecreasing radius). In another instance, robot 100 may move away fromthe object and then move in a direction that is somewhat tangential tothe object.

Robot 100 may decrease the cleaning speed to a reduced speed at aconstant rate, for instance, at a non-linear or exponential rate. Thefull cleaning speed of robot 100 may be about 300 mm/s and the reducedcleaning speed of robot 100 may be about 100 mm/s.

FIG. 10 shows kinetic bump sensors 132, floor proximity sensors 140 andan attachment brace 142 which may be used with robot 100 for detectingan adjacent floor. Kinetic bump sensors 132 may sense collisions betweenrobot 100 and objects in the robot's forward path. Floor proximitysensors may be carried by chassis 102 and be used to sense when robot100 is near a “cliff”, such as a set of stairs. Floor proximity sensors140 may send signals to controller 108 indicating whether or not a cliffis detected. Based on signals from the floor proximity sensors 140,controller 108 may direct drive system 104 to change speed or velocityto avoid the cliff.

FIGS. 11 and 12 show side and exploded views of a floor proximity sensor140. Floor proximity sensor 140 has a body with a forward section 144, arear section 146, an emitter 148, a receiver 150, and a cover 152.Emitter 148 and receiver 150 may be capable of emitting and receivinginfrared light. Emitter 148 and receiver 150 are arranged within theforward and rear body sections 144, 146 at an angle so that their axesline up at a point beneath robot 100 at the approximate floor distance.

FIG. 13 shows an exploded view of cover 152. Cover 152 consists of alens 154 and a cover body 156. Lens 152 may be transparent to infraredlight and cover body 156 may be opaque to facilitate focusing emissionssent from emitter 148. The forward edge 158 of cover 152 is elevatedabove its rearward edge 159 to aid in reducing dust build up and toensure that light is received by receiver 150 primarily when sensor 140is positioned correctly over a floor and a reduced amount is receivedwhen sensor 140 is over a “cliff”. In some implementations, cover 152 isconstructed using a material with anti-static (dissipative orconductive) properties, such as an anti-static polycarbonate, copperoxide doped or coated polycarbonate, anti-static Lexan “LNP” availablefrom General Electric, Inc., anti-static polyethylene, anti-staticABS/polycarbonate alloy, or other like material. One example includesABS 747 and PC 114R or 1250Y mixed with antistatic powder. Preferably,the robot shell, chassis, and other parts are also anti-static (e.g.,antistatic ABS), dissipative and/or conductive, at least in part inorder to ground the anti-static cover 152. The cover 152 may also begrounded by any conductive path to ground. When the coverage robot 100traverses a floor, a cover 152 without anti-static properties can becomeelectrostatically charged (e.g., via friction), thereby having apropensity to accumulate oppositely charged debris, such as fuzz, whichmay obstructing a sensing view of the emitter 148 and receiver 150.

In cases where the floor proximity sensor 140 is properly placed on afloor, light emitted from emitter 148 reflects off the floor and back toreceiver 150, resulting in a signal that is readable by controller 108.In the event that the floor proximity sensor 140 is not over a floor,the amount of light received by receiver 150 is reduced, resulting in asignal that may be interpreted by controller 108 as a cliff.

FIG. 14 is an exploded view showing an example of the caster wheelassembly 116. Caster wheel assembly 116 is separately and independentlyremovable from the chassis 102 and the coverage robot 100. The casterwheel assembly 116 includes a caster wheel housing 162, a caster wheel164, a wheel-drop sensor 166, and a wheel-floor proximity sensor 168.

The caster wheel housing 162 carries the caster wheel 164, the wheeldrop sensor 866, and wheel-floor proximity sensor 168. The caster wheel164 turns about a vertical axis and rolls about a horizontal axis in thecaster wheel housing 162.

The wheel drop sensor 166 detects downward displacement of the casterwheel 164 with respect to the chassis 102. The wheel drop sensor 166determines if the caster wheel 164 is in contact with the work surface.

The wheel-floor proximity sensor 168 is housed adjacent to the casterwheel 164. The wheel-floor proximity sensor 168 detects the proximity ofthe floor relative to the chassis 102. The wheel-floor proximity sensor168 includes an infrared (IR) emitter and an IR receiver. The IR emitterproduces an IR signal. The IR signal reflects off of the work surface.The IR receiver detects the reflected IR signal and determines theproximity of the work surface. Alternatively, the wheel-floor proximitysensor 168 may use another type of sensor, such as a visible lightsensor. The wheel-floor proximity sensor 808 prevents the coverage robot100 from moving down a cliff in the work surface, such as a stair stepor a ledge. In certain implementations, the drive wheel assemblies 112,114 each include a wheel-floor proximity sensor.

FIG. 15 is an exploded view showing an example of the wheel-drop sensor166. The wheel drop sensor 806 includes an IR emitter 170 and an IRreceiver 172 in a housing 173. The IR emitter 170 produces an IR signal.The IR signal reflects from the caster wheel 164. The IR receiver 172detects the reflected IR signal and determines the vertical position ofthe caster wheel 164.

FIG. 16 is a cross-sectional view showing an example of the caster wheelassembly 116. The view shows a top surface 174 of the caster wheel 164from which the IR signal reflects. The IR receiver 172 uses thereflected IR signal to determine the vertical position of the casterwheel 164.

In some instances, drive system 104 may further include a validationsystem that validates the operability of the floor proximity sensorswhen all wheels drop. The validation is based on the inference that allwheels dropped are likely the result of a robot being lifted off thefloor by a person, and checks to see that all floor proximity sensors donot register a floor surface (either no reflection measured, or areflection that is too strong). Any sensor that registers a floorsurface or a too strong reflection (e.g., indicating a blocked sensor)is considered blocked. In response to this detection, the robot mayinitiate a maintenance reporting session in which indicia or lightsindicate that the floor proximity sensors are to be cleaned. In responseto this detection, the robot will prohibit forward motion until avalidation procedure determines that all floor proximity sensors areclear and are functional. For example, a mechanical switch sensor may bepositioned above castor wheel 168 at a location 176 that causes it toclose when the castor is depressed (e.g. it is pushed upwards by thefloor), thus providing a alternate signal to controller 108 that castorwheel 164 is on the floor.

Occasionally, an autonomous coverage robot may find itself entangledwith an external object, such as frills on the end of a rug or shoelaces dangling from a untied shoe. A method of disentangling anautonomous coverage robotic (such as robot 100) may initially includeplacing robot 100 on a floor surface, which should be considered toinclude instances when the robot starts itself from a dock (e.g., aftera significant delay, but nonetheless having been placed on the floor).Robot 100 autonomously moves forward across the floor surface whileoperating the cleaning heads 106 a, 106 b. Robot 100 may reverse biasedge cleaning head motor 118 in response to a measured increase (e.g.,spike or increase above threshold, rapid increase of a predeterminedslope) in motor current while continuing to maneuver across the floorsurface in an unchanged direction, working and/or cleaning the floorwithout interruption.

In some instances, robot 100 may move forward before (independently offorward motion control by the motion behaviors) reverse biasing therotation of edge cleaning head 106 a in response to an elevated cleaninghead motor current. Robot 100 may independently reverse the rotation ofedge cleaning head 106 a in response to an increased edge cleaning head106 a motor current for a period of time. The time period for increasedcurrent may be specified, for instance, in seconds. After reversebiasing the rotation of edge cleaning head 106, robot 100 may move in areverse direction, alter its direction of travel, and move in the newdirection.

In particular combination, the robot includes a main cleaning head 106 bextending across the middle of the robot, e.g., in a directiontransverse to the robot working path or substantially in a directionparallel to the main drive wheels, as well as an edge cleaning headwhich is arranged at the lateral side of the robot, in a position toextend the edge cleaning head beyond the perimeter of the robot in theside direction so as to clean beside the robot (as opposed to solelyunderneath the body of the robot). The main cleaning head 106 b includesat least one rotationally driven brush 111, and the edge cleaning head106 a includes at least one rotationally driven brush 120.

As shown in FIG. 9C, the main cleaning head 106 b is controlled by,e.g., a brush motor control process 930. The brush motor control processmonitors a current sensor of the main cleaning head motor, and when arapid current rise occurs (e.g., spike or rise above threshold,integrated or otherwise determined slope of a predetermined amount),optionally checks if the robot is moving forward (e.g., by monitoring aprocess, a flag indicating forward motion, or the main drive motorsdirectly). If the robot 100 is moving forward, without interrupting suchmotion (optionally isolated from the capability to do so as the robotmotion is controlled by independent behaviorally controlled drive), thebrush motor control process 930 applies a reverse bias to the brushmotor.

The reverse bias does not rapidly rotate the motor in the reversedirection so as to avoid winding the same entangled cord, string, ortassel about the brush in the opposite direction. Instead, the brushmotor control process 930 applies a slight bias, sufficient to keep therotation of the brush near neutral. When the robot 100 moves forward,the cord, string, or tassel pulling on the brush to unwind theentanglement will only transmit an attenuated torque in the reversedirection to the motor (e.g., because of a reduction gearbox between themotor and brush permitting back-driving the gearbox at a reversedmechanical advantage), but, combined with the reverse bias, theattenuated torque results in assisted but slow unwinding of theentangled brush, of increasing speed as more tension is applied by thecord or string, e.g., as the robot moves further away from the sitewhere the cord or string or tassel is fixed.

The reverse bias continues until a time out or until no pulling orjamming load (e.g., no entanglement) is detected on the motor, whereuponthe process ends and the cleaning head resumes normal rotation in adirection to clean the surface.

The edge brush 120 of the edge cleaning head 106 a is subject tosubstantially the same control in an edge brush motor control process960, in which the edge brush 120 rotation is reverse biased 962 in asimilar fashion (also shown in FIG. 9B).

Accordingly, both main 106 b and edge 106 a brushes are controlledindependently of one another and of robot motion, and each maydisentangle itself without monitoring or disturbing the other. In someinstances, each will become simultaneously entangled, and independentbut simultaneous control permits them to the unwound or self-clearing atthe same time. In addition, by having the brush motor under reactivecontrol (not awaiting a drive motor state or other overall robot state)and with only a slight reverse bias, the brush will be available tounwind as soon as any rapid current rise is detected, catching anentanglement earlier, but will not move in reverse by any amountsufficient to cause a similar entangling problem in the oppositedirection.

In some instances, because the motion control is independent of and doesnot monitor the brush state, the robot 100 continues to move forward andthe cleaning head 106 b begins to reverse bias the rotation of maincleaning head 111 after the robot 100 has proceeded some amount forward.In some instances, robot 100 may reverse the rotation of main cleaninghead 111 in response to an elevated cleaning head motor current for aperiod of time. After reversing the rotation of main cleaning head 111,robot 100 may move in a reverse direction, alter a drive direction, andmove in the drive direction.

FIGS. 17A-H illustrate examples of methods for disentangling coveragerobots with various configurations of cleaning heads. In general, thecleaning heads have rollers which may be driven by electric motors. Dirtand debris may be picked up by the cleaning heads and deposited in acontainer for later manual or automatic disposal. Electronic controldevices may be provided for the control of drive motors for changing thecoverage robot's direction, and also for the control of agitating brushrollers. Such methods may allow coverage robots to resume cleaningunattended after encountering an entanglement situation.

FIG. 17A shows a side view of a cleaning head 201 of a coverage robot200 with an agitating roller 202 in tangential contact with the worksurface. Roller 202 brushes up dirt 203 towards a suction duct 204 whichis integrated within a brush chamber 206. By using an air suctionstream, the collected debris 210 may be conveyed to a container 212.

If the movement of rollers 202 is blocked or obstructed to apredetermined or a settable extent, the cleaning head 201 may bestopped, allowing robot 200 to reverse direction with roller 202minimally powered in the reverse direction sufficiently enough torelease the obstruction. For example, if a cord has become wound aboutroller 202, the roller 202 may be disengaged and allowed to turn so thatthe cord unwinds as robot 200 retreats. Robot 200 may then resumeoperation of roller 202 in the original direction of rotation and resumerobot motion in the original direction.

FIG. 17B shows another example of disentanglement using robot 200 withthe addition of a brush roller 214. Brush roller 214 may be driven bythe same or a different motor and rotate normal to the working surface.Brush roller 214 sends dirt 216 from the edges of robot 200 to a pickuparea 218 of roller 202.

In this example, if the movement of either rollers 202 or 212 is blockedor obstructed to a predetermined or a settable extent, cleaning head 201may be stopped, allowing robot 200 to reverse direction with rollers202, 212 minimally powered in the reverse direction sufficiently enoughto release the obstruction. For example, if a cord becomes wound abouteither roller 202 or 212, the roller 202 or 212, or both, may bedisengaged and allowed to turn so that the cord unwinds as robot 200retreats. Robot 200 may then resume operation of rollers 202, 212 in theoriginal direction of rotation and resume robot motion in the originaldirection.

FIG. 17C shows a below view of a coverage robot 240 and a side view of acleaning head 242 within it. A first brush roller 244 and a second brushroller 246 are in tangential contact with the work surface. Rollers 244and 246 may be rotated by a single or multiple motors for the purpose ofagitating the work surface and dynamically lifting debris 248 trappedbetween them, towards a suction duct 250 which is integrated withinbrush chamber 252. By means of an air suction stream 254, the collecteddebris 256 may be conveyed to a container 258.

If the movement of rollers 244, 246 is blocked or obstructed to apredetermined or a settable extent, rollers 202, 212 may be stopped,allowing robot 240 to advance forward, as shown by arrow 260, with therollers 202, 212 minimally powered in the reverse direction sufficientlyenough to release obstruction, and resume operation of the roller motorin the original direction of rotation.

FIG. 17D shows robot 240 performing an alternate example method fordisentanglement. If the movement of the agitating rollers 244, 246 isblocked or obstructed to a predetermined or a settable extent, therollers 244, 246 may be disengaged (i.e. not actively driven). Robot 240may then reverse directions, as shown by arrow 262, with rollers 244,246 minimally powered in the reverse direction sufficiently enough torelease the obstruction, upon which rollers 244 246 may be reengaged intheir original direction of rotation and robot 240 resumes driving inits original direction (shown by arrow 264).

FIG. 17E shows a side view of a coverage robot 270 with three rollers.Robot 270 has a cleaning head 272 and a side brush 274. Cleaning head272 has a normal agitating roller 276 and a counter-rotating agitatingroller 278. Agitating rollers 276 and 278 may be rotationally drivenparallel to each other and to the work surface and brush roller 274 maybe driven normally to the work surface by electric motor(s) (not shown).Brush roller 274 may pre-sweep the work surface and pushing dirt anddebris towards the agitating rollers 276, 278, as shown by arrow 279.Agitating rollers 276, 278 may push dirt 280 towards a suction duct 282which is integrated within a brush chamber 284. By using an air suctionstream, the collected debris 288 may be conveyed to a container 290.

If the movement of agitating rollers 276, 278 is blocked or obstructedto a predetermined or a settable extent, the roller motor(s) may bestopped or temporarily activated in the opposite direction in an attemptto remove the blockage or obstruction. The roller motor(s) may thenresume operation in the original direction of rotation.

FIG. 17F illustrates another example of a method for disentanglingcoverage robot 270. If the movement of agitating rollers 276, 278 isblocked or obstructed to a predetermined or a settable extent, theroller motor(s) may be stopped or temporarily activated in the oppositedirection. The roller motor(s) may then resume driving rollers 276, 278in the original direction of rotation while simultaneously reversing thedirection of travel of robot 270 or imparting a twisting motion aboutits axis. Robot 270 may then resume motion in the original direction.

FIG. 17G shows a side view and a bottom view of a coverage robot 300with two rollers and two air ducts. Robot 300 has a cleaning head 302 anormal agitating roller 304 and a counter-rotating agitating roller 306.Agitating rollers 304 and 306 may be rotationally driven parallel toeach other and to the work surface by electric motor(s) (not shown).

Rollers 304, 306 may dynamically lift and push dirt and debris 307towards a primary air duct 308 which is integrated within a brushchamber 312. Dirt and debris that are passed over by rollers 304, 306may encounter a secondary air duct 310 located be hind the rollers. Asuction stream generated by an air suction motor (not shown) may conveythe collected dirt and debris via the ducts 308, 210 to a container 314.Associated electronic control devices provide control to drive motorsfor turning and changing direction of robot 300, and also fordirectional control of the agitating rollers 304, 306.

If the movement of the agitating rollers 304, 306 is blocked orobstructed, then the control device do one or more of stopping orminimally powering the roller motor(s) in the reverse direction, thenresume operating the roller motor in the original direction of rotation.Simultaneously, robot 300 may at least momentarily reverse its directionor imparting a twisting motion about its axis and then resuming motionin its original direction.

FIG. 17H shows another example of a disentangling method, involvingrobot 300 with the addition of a brush roller 316. Brush roller 316 hasan axis of rotation normal and may be driven by an existing or dedicatedelectric motor. Brush roller 316 may pre-sweep the work surface and pushdirt and debris 307 towards the agitating rollers 304, 306 (as shown byarrow 318). Dirt and debris may then be removed as described above.

If the movement of the agitating rollers 304, 306 is blocked orobstructed, the control device may stop or minimally power the rollermotor(s) in the reverse direction reverse, then resume operating theroller motor in the original direction of rotation. Simultaneously,robot 300 may at least momentarily reverse its direction or imparting atwisting motion about its axis and then resuming motion in its originaldirection.

Referring to FIG. 18, an autonomous coverage robot 1800 includes a body1810, a drive system 1820 disposed or mounted on the body 1810 andconfigured to maneuver the robot 1800 over a surface. The robot 1800includes a cleaning assembly 1830 disposed on the body 1810. Thecleaning assembly 1830 includes a cleaning assembly housing 1832, afirst cleaning roller 1834 (e.g., a brush with bristles 1834 a and/orflaps 1834 b) rotatably coupled to the cleaning assembly housing 1832, asecond cleaning roller 1836 (e.g., a roller having flexible flaps 1836b) rotatably coupled to the cleaning assembly housing 1832, and acleaning drive motor 1838 driving the first and/or second cleaningrollers 1834, 1836. The first and second cleaning rollers 1834, 1836 maybe driven in the same rotational direction or in opposite directions, soas to move debris between, up, and over the cleaning rollers 1834, 1836into a cleaning bin 1900. The cleaning bin 1900 may be removablyattached to the body 1810 of the robot 1800. In some examples, the robotincludes a castor wheel assembly 116 (e.g., as described earlier withrespect to FIGS. 14-16) and/or a bumper 130 having bumper switches 132and/or proximity sensors 134 (e.g., as described earlier with respect toFIGS. 8A and 8B).

Referring to FIGS. 19A-19G, the cleaning bin 1900 includes a cleaningbin body 1910, which may have upper and lower portions 1910 a and 1910 b(FIG. 19B) as well as forward and rearward portions 1910 c, 1910 d (FIG.19G). The cleaning bin body 1910 defines an inlet opening 1912configured to receive debris agitated by the cleaning assembly 1830 foraccumulation in a holding portion 1914 in pneumatic communication withthe inlet opening 1912 of the cleaning bin body 1910. In someimplementations, the cleaning bin 1900 includes an access door 1916movably attached to the cleaning bin body 1910 (e.g., by a hinge orgroove to slide in). The access door 1916 is pivotable or slidablebetween an open position that allows access to the holding portion 1914for removal of gathered debris.

The cleaning bin 1900 may include an air mover 1920 (e.g., vacuum orfan) that may include a motor 1922 coupled to an impeller 1924 forpulling air through an air pathway 1926 of the air mover assembly 1922.In the examples shown, the air mover 1920 is disposed within thecleaning bin body 1910; however, the air mover 1920 may be disposedexternal to the cleaning bin body 1910 as well. Placement of the airmover 1920 inside the cleaning bin body 1910 allows various shapes orform factors of the cleaning bin body 1910 to match a shape or formfactor of the robot body 1810, such as an overall circular or puckshape. In some examples, the air mover 1920 is disposed substantially inthe upper and rearward cleaning bin body portions 1910 a, 1910 d, thusleaving open the holding portion 1914 substantially in the lower andforward cleaning bin body portions 1910 b, 1910 c. The air mover 1920defines a longitudinal axis 1921 disposed at an angle β of between about15° and about 75° (preferably about 60°) with respect to a longitudinal1911 axis defined by the cleaning bin body 1910. In some examples, anentrance of the air pathway 1926 is disposed along the longitudinal axis1921 of the air mover 1920, which creates an air flow at least partiallyalong the longitudinal axis 1921. Referring to FIG. 19G, in someimplementations, during operation of the cleaning bin 1900, the airmover 1920 draws a continuous flow of air 1905 into the inlet opening1914 of the cleaning bin body 1910, down toward and/or into the lowercleaning bin portion 1910 b (for depositing debris) and upward into theair pathway 1926. As a result, debris is generally deposited in thelower cleaning bin portion 1910 b first and accumulated upwardly intothe upper cleaning bin portion 1910 a. The air pathway 1926 may be inpneumatic communication with an exit 1918 of the cleaning bin body 1910.In some examples, the exit opening 1918 is located on the rearwardcleaning bin portion 1910 d and/or the upper cleaning bin portion 1910a.

An air mover guard 1930 may be disposed over the air mover 1920 orbetween the air mover 1920 and the holding portion 1914. The air moverguard 1930 includes a filter 1932 (e.g., filter paper, wire screen,etc.) configured to allow air to pass therethrough, while preventingpassage of debris therethrough. In the examples shown, the air moverguard 1930 defines an arcuate shape, but may be planar or other shapesas well. The arcuate shape of the air mover guard 1930 helps directaccumulation of debris in the holding portion 1914 to fill substantiallyin a lower rear portion, progressing upward and forward, untilcompletely filled. Furthermore, the air mover guard 1930 may beasymmetrically shaped (e.g., arcuate and tapering in width), such thatthe air mover guard 1930 is received by the cleaning bin body 1910 in asingle orientation. For example, when a user removes the air mover guard1930 to clean the filter 1932, the user is forced to position the airmover guard 1930 in a single orientation for placement back into thecleaning bin 1900, thus insuring that the user doesn't place the airmover guard 1930 in backwards, thus exposing any remaining debris on thefilter 1932 to the air mover 1920.

In some implementations, the cleaning bin 1900 includes a roller scraper1940 configured to engage or scrape a cleaning roller 1834, 1836 of thecleaning assembly 1830 for removing filaments or debris caught on thecleaning roller 1834, 1836. In the examples shown, the roller scraper1940 engages or scrapes the first cleaning roller 1834. The rollerscraper 1940 defines an edge or lip 1942 for engaging the first cleaningroller 1834 to peel filaments (e.g., hair) off of the cleaning roller1834. The edge 1942 may be a substantially linear edge disposedsubstantially parallel to and substantially spanning the first cleaningroller 1834. Referring to the example shown in FIG. 19F, the edge 1942of the roller scraper 1940 is disposed an interference distance D ofbetween about 0.25 mm and about 3 mm (preferably about 0.75 mm) into theouter diameter φ of the first cleaning roller 1834. The roller scraper1940 generally scrapes or peels filaments off of the engaged cleaningroller 1834 before the filaments can wrap tightly around the cleaningroller 1834 (e.g., before filaments wrap around smaller diameters of theroller, such as a core or axle). As filaments and debris are lifted orknocked off the engaged cleaning roller 1834, they are pulled by the airmover 1920 (via an air flow) into the holding portion 1914 of thecleaning bin 1900.

In some implementations, at least one cleaning roller 1834, 1836 createsa flow of air into the inlet opening 1912 (i.e., entrance) and throughthe cleaning bin 1900 (e.g., without the use of the air mover 1920). Theat least one cleaning roller 1834, 1836 not only agitates particulate,but also captures airborne particulate by creating a negative pressurezone in or near the inlet opening 1912 and/or the holding portion 1914of the cleaning bin 1900 for accumulation therein. Creating an overallnegative pressure in the cleaning bin 1900 aids settling agitated andcaptured debris in the cleaning bin 1900.

In the example shown in FIG. 18, the cleaning assembly 1830 includes anair guide 1840 (e.g., duct) disposed substantially over the cleaningrollers 1834, 1836 for providing an air pathway 1842 from below therobot body 1810 past the first and second cleaning rollers 1834, 1836and into the inlet opening 1912 of the cleaning bin 1900. The air mover1920 and/or the at least one cleaning roller 1834, 1836 creates anegative pressure inside the cleaning bin 1900 for drawing air anddebris (e.g., agitated by the cleaning rollers 1834, 1836) from belowthe robot body along the air pathway 1842 into the holding portion 1914of the cleaning bin for holding. The negative pressure also drawsfilaments and debris scraped from the first cleaning roller 1834 by theroller scraper 1940 into the holding portion 1914 of the cleaning binfor holding as well. The air guide 1840 may be arranged to direct airand/or debris flowing past the first and second cleaning rollers 1834,1836 along a path substantially tangent to one of the cleaning rollers1834, 1836 and coincident with a point slightly above the center line ofthat cleaning roller 1834, 1836. Such an arrangement can help feedfilaments (e.g., hair) into the cleaning bin 1900 rather than followingaround one of the cleaning rollers 1834, 1836.

Referring to FIGS. 18-19C, in some implementations, the cleaning bin1900 includes a latch 1950 for securing the cleaning bin 1900 to therobot 1800. The latch 1950 may be spring biased and button actuatable.The cleaning bin 1900 may also include at least one electrical connector1960 for establishing electrical communication between the cleaning bin1900 and the robot 1800 (e.g., via a corresponding electrical connectorof the robot). The electrical connector 1960 provides power to the airmover 1920. In some examples, the electrical connector 1960 providescommunication (e.g., network communication) with a controller of therobot 1800. The cleaning bin 1900 may include an air mover body cover1928 which is received by the exit 1918 of the cleaning bin body 1910and defines apertures (e.g., slots) 1929 for air flow therethrough. Theair mover body cover 1928 provides an access way for accessing andmaintenance of the air mover 1920.

Referring to FIG. 20, in some implementations, a cleaning bin 2000includes a cleaning bin body 2010 having a debris entrance 2012 inpneumatic communication with a holding portion 2014 of the cleaning binbody 2010. The cleaning bin body 2010 includes an air conduit 2020 thatextends from a forward portion 2011 of the cleaning bin body 2010 to arearward portion 2013 of the cleaning bin body 2010. The air conduit2020 is in pneumatic communication with an air mover of the robot 1800while the cleaning bin 2000 is received by the robot 1800. The air moverdraws air (and debris) into the holding portion 2014 of the cleaning binbody 2010 by creating a negative pressure in the holding portion 2014 ofthe cleaning bin body 2010 with respect to outside of the cleaning bin2000. In some examples, the air mover is a cleaning roller 1834, 1836,while in other examples, the air mover is a fan or blower. The cleaningbin includes a roller scraper 2040 configured to engage or scrape acleaning roller 1834, 1836 of the cleaning assembly 1830 for removingfilaments or debris caught on the cleaning roller 1834, 1836. In theexample shown, the roller scraper 2040 engages or scrapes the firstcleaning roller 1834 and defines an edge or lip 2042 for engaging thecleaning roller 1834 to peel filaments (e.g., hair) off of the cleaningroller 1834. The edge 2042 may be a substantially linear edge disposedsubstantially parallel to and substantially spanning the cleaning roller1834. The roller scraper 2040 may be configured as the roller scraper1940 of the cleaning bin 1900 discussed with respect to FIG. 19F.

Other robot details and features combinable with those described hereinmay be found in the following U.S. patent applications entitled“AUTONOMOUS COVERAGE ROBOT NAVIGATION SYSTEM” having assigned Ser. No.11/633,869; “MODULAR ROBOT” having assigned Ser. No. 11/633,886; and“ROBOT SYSTEM” having assigned Ser. No. 11/633,883, the entire contentsof the aforementioned applications are hereby incorporated by reference.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the following claims. Accordingly, otherimplementations are within the scope of the following claims.

What is claimed is:
 1. An autonomous coverage robot comprising: a body;a drive system disposed on the body and configured to maneuver therobot; and a cleaning assembly disposed on the body and configured toengage a floor surface while the robot is maneuvered across the floorsurface, the cleaning assembly comprising: a driven cleaning rollerdefining a rotational center about which the cleaning roller isconfigured to rotate; a cleaning bin disposed on the body for receivingdebris agitated by the cleaning roller, the cleaning bin comprising: acleaning bin body having a cleaning bin entrance disposed adjacent tothe cleaning roller, the cleaning bin body having a holding portion inpneumatic communication with the cleaning bin entrance for receivingdebris; and a roller scraper disposed on the cleaning bin body forengaging the cleaning roller, the roller scraper being positioned suchthat, during operation of the robot, the roller scraper engages adownwardly rotating portion of the cleaning roller; and an air moveroperable to move air into the cleaning bin entrance; wherein the rollerscraper is disposed at a lower edge of the cleaning bin entrance duringthe operation of the robot and arranged to engage the cleaning rollerabove its rotational center, the lower edge being substantially linear,substantially parallel to the cleaning roller, and of a lengthsufficient to substantially span the cleaning roller.
 2. The robot ofclaim 1, wherein the roller scraper is disposed an interference distanceD of between about 0.25 mm and about 3 mm into an outer diameter of thecleaning roller.
 3. The robot of claim 2, wherein the roller scraper isdisposed an interference distance D of about 0.75 mm into the outerdiameter of the cleaning roller.
 4. The robot of claim 1, wherein theair mover is disposed inside the cleaning bin body substantially near anupper rear portion of the cleaning bin body.
 5. The robot of claim 4,wherein the air mover defines a longitudinal axis disposed at an angleof between about 15° and about 75° with respect to a longitudinal axisdefined by the cleaning bin body.
 6. The robot of claim 1, furthercomprising an air mover guard disposed between the air mover and theholding portion of the cleaning bin, the air mover guard comprising afilter for filtering debris from air passing therethrough.
 7. The robotof claim 6, wherein the air mover guard is removably attached to thecleaning bin body and defines an asymmetric shape, wherein the air moverguard is received by the cleaning bin body in a single orientation. 8.The robot of claim 1, wherein the air mover comprises at least onecleaning roller.
 9. The robot of claim 1, wherein the cleaning assemblycomprises: a cleaning assembly housing; and first and second drivencleaning rollers rotatably coupled to the cleaning assembly housing, thefirst cleaning roller comprising bristles and the second cleaning rollercomprising flexible flaps; wherein the roller scraper is disposed toengage the first cleaning roller.
 10. The robot of claim 1, wherein thecleaning assembly further comprises an air guide configured to direct anair flow of the air mover over the cleaning roller and into the cleaningbin entrance.
 11. The robot of claim 10, wherein the air guide isarranged to direct the flow of air along a path substantially tangent tothe cleaning roller and coincident with a point slightly above therotational center of the cleaning roller.
 12. The robot of claim 1,wherein the cleaning bin comprises an access door comprising the rollerscraper, the access door being disposed at the cleaning bin entrance andbeing hingedly attached to the cleaning bin body.
 13. The robot of claim1, wherein the air mover is configured to draw air from below the robot,past the cleaning roller, and through the cleaning bin entrance and theholding portion.
 14. A cleaning bin for a coverage robot, the cleaningbin comprising: a cleaning bin body having a cleaning bin entrance, thecleaning bin body having a holding portion in pneumatic communicationwith the cleaning bin entrance for receiving debris; an air moverdisposed on the cleaning bin body and configured to draw air into thecleaning bin entrance; and a roller scraper disposed on the cleaning binbody for engaging a cleaning roller of the robot above a rotationalcenter of the cleaning roller, the roller scraper being positioned suchthat, during operation of the robot, the roller scraper engages adownwardly rotating portion of the cleaning roller; wherein the rollerscraper is positioned so as to be disposed at a lower edge of thecleaning bin entrance during the operation of the robot, the lower edgebeing substantially linear, substantially parallel to the cleaningroller, and of a length sufficient to substantially span the cleaningroller.
 15. The cleaning bin of claim 14, wherein the air mover isdisposed inside the cleaning bin body substantially near an upper rearportion of the cleaning bin body.
 16. The cleaning bin of claim 15,wherein the air mover defines a longitudinal axis disposed at an angleof between about 15° and about 75° with respect to a longitudinal axisdefined by the cleaning bin body.
 17. The cleaning bin of claim 14,further comprising an air mover guard disposed between the air mover andthe holding portion of the cleaning bin, the air mover guard comprisinga filter for filtering debris from air passing therethrough.
 18. Thecleaning bin of claim 17, wherein the air mover guard is removablyattached to the cleaning bin body and defines an asymmetric shape,wherein the air mover guard is received by the cleaning bin body in asingle orientation.
 19. The cleaning bin of claim 14, further comprisingan access door comprising the roller scraper, the access door beingdisposed at the cleaning bin entrance and being hingedly attached to thecleaning bin body.
 20. The cleaning bin of claim 14, wherein the airmover is configured to draw air from below the robot, past the cleaningroller, and through the cleaning bin entrance and the holding portion.21. A cleaning bin for a coverage robot, the cleaning bin comprising: acleaning bin body having a cleaning bin entrance, the cleaning bin bodyhaving a holding portion in pneumatic communication with the cleaningbin entrance for receiving debris; an air conduit in pneumaticcommunication with the holding portion, the air conduit establishingpneumatic communication with an air mover of the robot while received bythe robot, the air mover being configured to draw air into the cleaningbin entrance; and an access door disposed at the cleaning bin entranceand hingedly attached to the cleaning bin body, the access doorcomprising a roller scraper for engaging a cleaning roller of the robotabove a rotational center of the cleaning roller, the roller scraperbeing positioned such that, during operation of the robot, the rollerscraper engages a downwardly rotating portion of the cleaning roller;wherein the roller scraper is positioned so as to be disposed at a loweredge of the cleaning bin entrance during the operation of the robot, thelower edge being substantially linear, substantially parallel to thecleaning roller, and of a length sufficient to substantially span thecleaning roller.
 22. The cleaning bin of claim 21, wherein the air moveris configured to draw air from below the robot, past the cleaningroller, and through the cleaning bin entrance and the holding portion.